I changed the L around a bit and had it dyno tuned this morning.

With factory exhaust, JLP CAI and a 4lb. lower, it made 387HP & 475 TQ. This was in December and the air temp was in the mid 70's. The tuner said my blower belt was slipping and that exhaust would probably help.

So...

Today, I changed the lower to a 6lb., added a Metco belt tensioner and added the Magnaflow cat-back.

It made 404 HP but only 455 TQ. Also, the torque was way up at 4650 RPM, instead of the 3500 RPM it was with the 4 lb. lower. Air temps were in the high 80's.

Sam (the tuner) says he expected a bit of a drop with the Magnaflow, but that the 2 extra pounds of boost should have helped offset it. He was stumped and wants me to come back to figure it out. (I had to get to the office so I couldn't hang around)

He showed me several files from other L's that had similiar mods done and my HP seems average, but the torque is low and at too high an RPM.

The one variable is I have updated the firmware on my Predator between the two tunes. Is there any way the tune isn't "compatible" with the newer firmware in my Predator ?

BTW - this is on a Mustang dyno.

Any ideas ??

 

Were both runs done on the same dyno Mustang dyno's read a little lower. I have Manaflow exhaust with x-pipe and a 6#er and pulled 408.6/522.2 on a dyno jet.
jeff

 

I had a similar deal with my torque, I'm running 4lb lower and Apten Port and with my first tune was a dyno tune and I pulled 400/474 STD and was only running 13.6@101 with 2.0 60fters. Then I tried a different tune and got her up a t 417/498 SAE runned 13.3@105. So in my case I had a bum tune...

 

So, who did your 2nd tune ??

 

I made 404 HP & 488 TQ on a Mustang dyno, and I was pig rich. 11.2 A /F 's



______DON _____
TEAM PSP

 

Mustang dyno's show lower tq readings due to the way it loads for vehicle weight.
You're #s look fine. Take it to the track...that's where it counts!

 

I run a Steig port and 4# lower, 17* of timing and a A/F of 11.2 across the board. At full weight I've ran 12.63 @ 109 on F1s consistantly in 60* air. No dyno #s yet with the port. I get my A/F from my WBC.
Old 4#, tune, plugs and intake I was at 404/508 with an A/F of 11.8 and ran 12.6s @ 108 on slicks in 45* air.
I think it's safe to assume I picked up at least 20hp/20tq at the rear wheels.

So to answer the original question of this post................It's all in the tune!

 

BOTH dyno sessions were on the same Mustang dyno. I lost torque going to a bigger lower pulley and Magnaflow cat-back.

The dyno isn't the question, the results are.

It might be in the tune, but I think something else may be up - the torque peak is coming way higher in the RPM band...

That is the question I am seeking advice on...

 

I would take it back to the dyno and put the original pulley from the first dyno tune back on it and see what happens.